Area Code 603 — Manchester, New Hampshire

NANP area code

603

UTC−5, UTC−4 during daylight saving

State
New Hampshire
Primary city
Manchester
Time zone
Eastern
In service
1947

The code reaches 253 communities and 10 counties across New Hampshire.

Was this call legitimate?

The area code itself carries no risk signal. 603 is assigned to Manchester, New Hampshire, so a call from it is consistent with a real caller in that area — but the digits alone prove nothing, because they can be forged.

Caller ID is set by whoever places the call, not verified by the network. That is why neighbour spoofing works: an operation anywhere in the world can display a number that matches the area code — and often the first three digits after it — of the person being called, so the call looks local. Every community in the 603 territory is a plausible-looking origin for a forged 603 number, which is why one can be made to look like a neighbour to so many people.

If you did not recognise the call: let it go to voicemail — a legitimate caller with real business will leave one. Do not return the call using the number shown; look the organisation up independently and call the number you found. Never confirm personal details, card numbers, or one-time codes to someone who called you, however plausible the number looked.

Codes.zone publishes no complaint counts, risk scores, or caller identities. We hold no data on individual numbers and will not estimate what we cannot source.

Local time and when to call back

Time there now

Eastern · UTC−5, UTC−4 during daylight saving

Reasonable callback window

8:00 AM – 9:00 PM

local time in Eastern

Federal rules bar telemarketing calls to a residence outside 8:00 AM–9:00 PM in the called party's own time zone. It is a sensible bound for a personal callback too — and a caller who rang you well outside it was not observing it.

Overlay codes

603 is the only area code serving its territory — it has no overlay in the current numbering plan for New Hampshire. Where a region has no overlay, a number's area code still corresponds to a single geographic area.

Cities served

largest 20 by ZIP count
Communities served by area code 603, ranked by how many ZIP codes each holds.
CityZIP codesCounty
Manchester8Hillsborough County
Nashua5Hillsborough County
Concord4Merrimack County
Portsmouth4Rockingham County
Rochester4Strafford County
Dover3Strafford County
Tilton3Belknap County
Hampton2Rockingham County
Keene2Cheshire County
Laconia2Belknap County
Lebanon2Grafton County
Acworth1Sullivan County
Alstead1Cheshire County
Alton1Belknap County
Alton Bay1Belknap County
Amherst1Hillsborough County
Andover1Merrimack County
Antrim1Hillsborough County
Ashland1Grafton County
Ashuelot1Cheshire County

233 further communities not listed. All New Hampshire area codes →

Each point is a community served by 603, plotted from its record coordinates. The outline is the convex envelope of those points — a footprint, not a boundary.
  • Reference points and footprint
  • Not an official NANPA boundary
  • Not a USPS delivery area

Scope every community matched to 603. Source geoinfo-dataset (full_dataset) ZIP→NPA (2018 snapshot), GeoNames US postal codes (2026-07 postal dump) and Census 2024 county Gazetteer (2024 Gazetteer). Updated . Coordinates are place reference points, not boundaries.

Counties

Prefixes inside 603

We do not publish the NXX prefixes inside 603. The assignment of prefixes to rate centres comes from LERG routing data, which is proprietary, and we will not estimate it from postal data — ZIP codes and telephone prefixes do not map onto each other. Awaiting a clean-rights NPA-NXX source.